Prenylated chromones and coumarins from the leaves of Billburttia capensoides Sales & Hedge (Apiaceae)

Billburttia Sales & Hedge is a new genus endemic to Madagascar, which belongs to the Apiaceae family and comprises of two species, namely Billburttia capensoides and B. vaginoides. The present work was undertaken in a view to explore secondary metabolites from the leaves of B. capensoides, contributing to have more knowledge on the chemical profile of this species. Liquid-liquid partition followed by chromatographic separation of its ethanolic extract led to the isolation of two new prenylated chromones, 2'R-hydroxy-7-O-methylallopeucenin and the known coumarins imperatorin and xanthotoxin. Their chemical structures were established on the basis of spectroscopic methods including nuclear magnetic resonance (NMR) and high resolution mass spectrometry, and by comparison with the reported data in the literature. The structure of the compound 3 was confirmed by single-crystal X-ray diffraction. This is the first report on the nonvolatile constituents of B. capensoides. The presence of imperatorin and xanthotoxin supported that the new endemic genus Billburttia belongs to the Apiaceae family. All these data may induce further research on this species in order to find new chemical entities with biological and chemotaxonomic interests.